The elements of statistics for clinical readers

Statistical courses usually emphasize teaching the mathematical properties of methods to perform statistical significance testing. To interpret clinical studies, however, the reader needs to know only the purpose of the statistical methods, not their mathematical basis. This purpose in most studies is to evaluate the association between a risk factor and an outcome. The evaluation has five components: (1) measure the strength of the association, (2) determine the probability that the observed association did not occur by chance alone, (3) find the range of probable values for the measure of association, (4) reduce the possibility that the association is invalid because of confounding factors, and (5) examine the possibility that the association does not apply equally well to all people because of modulating factors. By focusing on the purposes of the statistical evaluation, the reader will be less distracted by the specific mathematical formulations that provide little additional information to the clinician.